Crates is Good, you should get a good price. Ebay
can be finicky, have you listed it on TackTrader.com or Equinehits.com
EquineHits is free, they get a lot of hits, jut watch out for the scammers who want to send a check or pick it up by courier, etc.
Another BB with a huge following is horsegroomingsupplies.com/horse-forums - ads are free too, they are one of the largest Forums I have ever found.